import java.util.Scanner;

/**
 * @author zhaoqian
 * @create 2021/9/1 9:32
 */
public class lifang {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()){
            double v = in.nextDouble();         //牛顿迭代法
            double x = 1;
            double x1 = x - (x*x*x - v) / (3*x*x);
            while(x - x1 >0.000000001 || x - x1 < -0.000000001){        //判断精度
                x = x1;
                x1 = x - (x*x*x - v) / (3*x*x);
            }
            String result = String.format("%.1f",x1);
            System.out.println(result);


        }
    }
}
